This forum has given me a lot over the last few years, so thought I would give a little back in the form of this write-up. Haven’t seen a how-to on dropping and cleaning the transmission pan, hope this isn’t a duplicate.
There is already an excellent thread describing how to drain and fill the transmission fluid including the procedure to get into temp check mode and set the proper transmission fluid level with the engine running:
https://www.tacomaworld.com/threads/how-to-drain-refill-automatic-transmission.63851/
This post adds in steps to remove the pan, remove the filter, and clean both along with the four pan magnets. Then reinstall with a new gasket (and as I chose to do, new o-ring for the filter and new crush washers for the drain and overflow plugs).
Note: this procedure is for the A750F transmission. Your A/T P/N is listed on your driver’s door jamb above the tire PSI sticker. My vehicle is a 2015 DCSB V6 with 65k miles at the time of service.
Material and parts:
5 qts ATF (I used Toyota WS)
Filter o-ring P/N 90301-31014
Gasket P/N 35168-60010
Crush washers (2) P/N
35178-30010
Shop towels
Brake cleaner
PB blaster
Optional: should you choose to replace rather than clean the filter (or “strainer”), it is Toyota P/N 35330-60030 (2.7L) or P/N 35330-60050 (4.0L).
Tools:
24mm socket (fill plug)
14 mm socket (drain plug)
10 mm socket (pan bolts)
5 mm hex (overflow plug)
Torque wrench in ft-lbs
Torque wrench in in-lbs
5 quart metered clear bucket (recommended)
Drain container (I liked the Hopkins 16 qt variety because it’s shaped like the transmission pan)
Hand pump
Torque values derived from https://www.tacomaworld.com/threads/the-torque-spec-guide.318116/
Fill plug: 29 ft-lbs
Drain plug: 21 ft-lbs (note: see posts #4, #25 and #26 where other members state this torque value should be corrected to 15 ft-lbs and that 21 ft-lbs can damage the plug and/or pan. I can only reference the torque spec in the manual. If someone has an official updated reference for this I’d appreciate it)
Overflow plug: 15 ft-lbs
Bolts attaching filter to valve body: 7 ft-lbs or 84 in-pounds
Bolts attaching pan to transmission case: 39 INCH-pounds
Procedure:
Soak the fill, drain, overflow and pan bolts with PB blaster the day prior. Just in case.
Remove fill plug located high on passenger side of transmission case using the 24mm socket. Should come off with an o-ring attached. Note: this is not doable with a deep socket due to lack of clearance. I chose a six-sided shallow socket, which is hard to find apparently. Didn’t want to round off corners with a 12-sided, but opinions vary on the subject.
Position catch bucket and remove drain plug. This is the plug that sits lower on the pan and requires the 14 mm socket. Loosen overflow plug with 5mm hex socket once pan is drained.
In the photo above, taken from the driver’s side, the overflow plug is center and closest to the camera.
Reinstall drain plug but only hand tighten. This is just to prevent the next part from being any messier than necessary.
Remove (20) pan bolts with the 10mm socket in a star pattern. They have washers so take your time and make sure you retain each bolt and washer. Ensure the last two you leave are opposite and easy to access. Hold the pan firmly in place while removing the last two bolts, lower slowly and then place over bucket or drain container to remove both plugs and pour out any remaining fluid. Once the pan is low enough to pull away from the filter intake, some fluid will dump from the filter so be prepared. Keep a bucket or drain container under the transmission as it will continue to drip.
The gasket may stick to the pan or to the case. Pull free or gently pry loose with a non-metallic tool if necessary. Mine came off the pan easily. There is no sealant holding the gasket in place. Make sure you have a soft cloth to place the pan on.
Remove the four magnets, and clean the magnets and pan with brake cleaner. Ensure the mating surface of the pan is clean. Replace magnets.
Next, remove the four 10mm bolts holding the filter to the valve body and then remove the filter. It takes a bit of force. Be prepared for some more fluid to dump once the filter comes off. Keep track of the o-ring on the top of the filter where it connects to the valve body.
Cleaning the body of the filter with brake fluid is easy, but getting the grit off the screen is awkward because of the access. I just wiped it out as best I could with a shop towel. Be careful as the screen is fragile. I also replaced the o-ring but some might consider this overkill.
You could also choose to replace the filter.
All told, through this whole process I collected about 4.3 qts of fluid. I recommend pouring all the collected transmission fluid into a metered container in order to measure what was drained, to determine where you start with the refill.
Reinstall the filter with o-ring, it takes a hard push and kind of clunks into place. Torque bolts to spec in star pattern.
Clean mating surface of transmission case. Arrange new gasket in place on the transmission pan. Install two bolts to hold in place and hand tighten. It was a huge ass pain to keep the gasket in place on the pan while raising it to the case, because I did this whole procedure on my back on the floor of my garage with the transmission a foot or less from my face. Fun times! Some might put a drop of sealant on the four corners to hold the gasket in place, I was determined not to.
Install remaining bolts and torque to spec in star pattern. Congratulate yourself and drink copious beers.
At this point, install the drain plug with new crush washer and torque to spec, then install the overflow plug with new crush washer and only tighten slightly.
Add 1/3 more fluid than the total that was drained to transmission via fill port and then reinstall fill plug. I added about 5 quarts. Up to you whether or not to torque it down, because if nothing comes out when you go into temp check mode and open the overflow plug, you will need access back to the fill port to add more fluid.
From here, refer to the remainder of the fill procedures in the drain and fill thread linked above, starting with turning on the engine and cycling through all the gears. I stayed in each gear for 30 seconds and cycled through twice. Don’t forget to ensure you’ve properly torqued all three transmission plugs to spec.
Some notes: this gets awkward because all three socket head sizes are involved: 1/2, 3/8 and 1/4 inches. So plan ahead. On the overflow plug make sure your hex socket seats deep into the plug, and clean it or blow it out if needed. Also, finding the smaller inch-pound torque wrench was a pain in the butt. Harbor Freight was the only game in town, had one for $20. But overall the mechanical difficulty level was very low, and it was pretty satisfying to clean all the sludge off the pan and magnets in addition to replacing some of the fluid. I do plan on 3 more drain and fills over the next month so that I’ll have gotten to most of the overall fluid.
